AC system is perfect then. It really was not evaporator issue. It just needed cleaning at most, and they replaced the whole item unnecessarily.
Left side vents usually have slight lower airflow compared to right ones, but your issue seems like left side vent pipes are leaking air under dashboard, assuming that blower fan is clean and motor is in good health.
Turn on AC and at max speed, and feel air leaks with your hand under dashboard area on green highlighted areas and inside dashboard box (purple). Red is the path of airflow to Front air vents.
Also, check that when airflow is set to face only, it should only throw airflow at face only and not through legs, windshield airflow vents.
